In the practice of pest control, particularly insect control, there are two main factors which determine the effectiveness of the treatment: 1) the immediate action on the pests (known in the art as “knock-down action”); and 2) the long term action (known also as “residual action”). Effective knock-down insecticides include pyrethroids, organic phosphoric acid esters, neonicotinoids such as for example, imidacloprid, acetarniprid and phenyl pyrazoles (fipronil). Effective long term insecticides include insect growth regulators (IGR) of various types, e.g. chitin synthesis inhibitors. Current methods for achieving the desired effect include repeated treatments over time with insecticides which have an effective knock-down action. The disadvantages of repeated treatments are: a) the use of relatively large doses of insecticides over time, which may cause environmental hazards; and b) there are certain periods within the life cycle of the crop when treatments with effective knock-down insecticides are prohibited since they may be absorbed in the crop and/or may damage the crop. On the other hand, using long term active insecticides may aid in preventing repeated treatments, but may not be effective against certain insects which have reached a certain developmental stage in their life cycle. For example, the group of insecticides known as insect growth regulators (IGR), which generally have effective long term action, are almost ineffective against adult insects due to their low knock-down effect.
Combination treatments of knock-down and long term insecticides have been reported. U.S. Pat. No. 6,685,954 reports on the effectiveness of fipronil in combination with IGR of the juvenile hormone mimic group in the treatment of ectoparasites in mammals.
Insecticidal combinations are also described in WO2006/048868, WO99/18796 and WO95/33380.
The woolly apple aphid, Eriosoma lanigerum, is one of several species of aphids that can infest apple trees. Other aphid species found on apple trees are rosy apple aphid and green apple aphid. Such aphids may be found either in commercial orchards or in home plantings. Woolly apple aphid feeds mainly on apple, but may be found also on elm, pear, quince, hawthorn, mountain ash, and cotoneaster.
Woolly apple aphid is an indirect pest (insect) that weakens the tree by its feeding on bark and roots, which reduces tree health, prevents wounds from healing, and transmits perennial apple canker. Woolly apple aphid is also a direct pest when it infests fruit cores of some cultivars.
An insecticide can be applied if woolly apple aphid is detected at damaging levels on above-ground parts of trees. Insecticides are most effective if applied when the aphid is in the active crawler stage and is just moving up into the tree. This may occur in late-spring or not until mid-summer. Thorough coverage of the canopy is needed for the insecticide to be effective. Due to the aphids' waxy covering, high volume application is needed to get thorough spray coverage. A second application may be needed two weeks after the first if aphids continue to be detected.
Insecticides used to control woolly apple aphid are dimethoate (Cygon), endosulfan (Thiodan), chlorpyrifos (Lorsban), or methyl parathion (Penncap-M). These are contact insecticides from chemical groups which are not recommended because of their toxicological profile, some of them already banned. Also, with the time their efficacy was decreased.
Thus, although there are several treatments known in the art for controlling woolly apple aphids, those treatments are insufficient and/or they are considered toxicological.
A pesticide composition comprising imidacloprid and chlorpyrifos for control of apple aphid has been reported in CN1299596A.
It will be highly advantageous to have a new effective method for controlling woolly apple aphid.
There is a long felt need for an effective method of treating woolly apple aphid having reduced environmental, toxic and ecotoxic problems.
It is therefore a purpose of the invention to provide a method and composition for effective control of woolly apple aphid insect useful for plant protection, especially for controlling insect infested fruit trees, such as apple trees.